1. Field of the Invention
The present invention relates to a vertical pump; and more particularly to a motor support for a multistage vertical pump at high pressure, including vertical turbine solids handling (VTSH) pumps.
2. Brief Description of Related Art
VTSH pumps are known in the art which operate in an upright position and employ a bowl assembly including a rotary impeller submerged in a body of liquid or fluid to be pumped having entrained stringy material and other solids. VTSH pumps are typically efficient over a broad capacity range than conventional solids-handling pumps, and can be used with a wide variety of standard above-ground drives, thus eliminating the need for submersible drives.
Above ground components of vertical pumps are often subjected to mechanical resonance. The potential for mechanical resonance could exist if the system's natural frequency is too close to the operating speed. The buildup of large vibration amplitude causes contact wear between the bearings and bearing journals on the shaft. As a result, pumps as well as motor lives are shortened.
To prevent this problem at the design stage, a pump-motor system should be detuned in order to reduce its stiffness, lowering natural frequency response away from potential points of excitation. Traditionally, it's been achieved by (see FIG. 1):
1. Decreasing wall thickness of motor support;
2. Adding radial cutouts to the motor support;
3. Lengthening the height of the motor support;
4. Combination of one or more of the methods listed above.
However, using methods 1 and 2 are typically limited by the area of the motor support cross section needed to withhold hydraulic thrust of the pump, and motor torque transferred by the powertrain.
Using method 3 is usually limited by customer's constraints and requirements.
Other VTSH pumps are also known, including U.S. Pat. Nos. 4,063,849 and 5,496,150, where the '849 patent discloses a discharge pump having a discharge elbow with diametrically-opposing openings, and where the '150 patent discloses a VTSH pump having a discharge elbow without any such diametrically-opposing openings, which are both incorporated by reference in their entirety. See also U.S. Pat. No. 8,226,352, which is assigned to the assignee of the present patent application, and which is incorporated by reference in its entirety.
Based upon the aforementioned, there is a need in the industry for a better vertical pump design that overcome these problems in the known vertical pump designs.